Micrometer gauge for internal threads



March 17, 1931. 36pm r 1,797,122

MICROMETER GAUGE FOR INTERNAL THREADS Original Filed May 25, 1929 2 sheets-sheet 1 INVENTOR;

ATTORNEY.

March 17, 1931. F. J. BOHN MICROMETER GAUGE FOR INTERNAL THREADS Original Filed May 25, 2 Sheets-Sheet 2 III 4 III ATTORNEY.

r specification- I Figure 1. 1s a side elevation of a conven- Patented Man. 17, 1931 I UNITED STATES FRANK J. IBOHN, OF WASHINGTON, DISTRICT OF COLUMBIA MICBOMETER GAUGE FOR INTERNAL THREADS Original application filed May 25, 1929, Serial No. 365,980. Divided and this application filed April' 26, 1930. Serial No. 447,646.

My invention is an improvement in micrometer gauges, and relates more especially to that particular type employed for accurately measuring the internal threads of a cylinder between the walls for fitting one part within another, as for instance an externally threaded cylinder, bar, or shaft to an internally threaded cylinder, the present application being a division of the application filed by me May 25, 1929, Serial No. 365,980.

The primary object of my invention is to provide attachments for a conventional type of inside micrometer gauge which will adapt it for more conveniently and accurately measuring the internal screw threads of a cylinder to correspond with the diameter of external threads on a cylinder, bar, or shaft to be fitted tightly within the threaded portion of the cylinder.

A further object of my invention is to provide attachments for the above mentioned purpose-which can be applied to a well known type of micrometer gauge for inside measurements without requiring material alteration 2 thereof to receive the attachments, and which will not afi'ect theordinary use'of the micrometer gauge when desired.

A further object of my invention is to provide attachments for a micrometergauge in;

which the portions engaging the threads at opposite sides of the internally threaded bore of the cylinder are removable with respect to said attachments so that any one of'a vari.-

ety of engaging portions. may be used in connection with a single set of my improved end pieces or attachments.

With the foregoing principal objects. in view the present application relates specifically to the attachments for the outer end of the rod of the micrometer gauge, the companion application being restricted to the attachments atthe other end or head of the gauge, all ashereinafter fully described and specifically set forth in the appended claims.

In the drawings forming a part of this tional type otmiorome'ter gauge for measurmg internal diameters.

Fig. 2 is a similar view illustrating the application of my invention thereto.

Fig. 3 is a side elevation of the micrometer gauge with the attachments shown in longitudinal section.

Fig. 4 is a view illustrating the attachment for the rod of the micrometer gauge, the parts being separated.

Fig. 5 is a similar view of the attachment at the inner end on the head of the gauge.

Fig. 6 is a side elevation illustrating a modification of my invention to provide for longitudinal movement of the attachment on the outer end or rod of the micrometer gauge without disturbing the measurement.

Fig. 7 is a similar view, the parts of the slidable attachment being shown in section.

Figs. 8 and 9 show modifications in the formation of the outer ends of the attachment used at the inner end of the mocrometer gauge.

Fig. 10 is a view similar to Fig. 7 with the toothed portions of the end pieces detachably connected.

Figs. 11 and 12 are detail sectional views 7 of the end pieces at the outer end of the gauge.

Fig. 13 is a detail sectional view showing a modification of the set screw forming part of the swivel connection.

Figs. 14, 15, and 16 are views showing the threaded engaging teeth formed of wires.

Figs. 17 and 18 are detail views of different forms of points used at the outer end of the gauge. 85 Figs. 19 and 20 are modifications in the shape of the thread engaging teeth.

Fig. 21 is a sectional view of a modification of the attachment at the inner end of the gauge. I

Fig. 22 is a view of a standard type of micrometer gauge the inner end being broken away to show the attachment of the short rod or pin thereto.

Fig. 23 is a similar view showing the application of my attachment.

Fig. 24 is a detail view of this form of the attachment.-

Fi 25 is a detail view showing one form of. attac ing the wires to the cut-away teeth, and 1 Fig. 26 is a detailed view of the attachment with a single tooth such as shown in Fig. 20.

Like numerals of reference indicate; like parts in the several views of the drawings.

g My improved attachments are adapted to bejapplied to a micrometer gauge for inside measurements such as illustrated in the drawings, comprising a head having a short rod 21 for engaging the bore or internalthread of a cylinder, and-a member 22 slidable in said head and having a longer rod 23 secured therein by set screw 24, the sleeve portion at the inner end of the head having graduations registering with graduations on the slidable member. As'the micrometer gauge is of a conventional type and of well known construction further detail description of the same as well as the operation'thereof is un-' necessary. Y

In carrying out my invention as illustrated I in Figs. 2 to 9 inclusive (Sheet 1 of the drawings) the attachment at the inner end of the micrometer gauge comprises a member 25 having a socket 26 at one end, and a pintle 27 at the other'end on which is swivelled a member or end piece 28 having projecting teeth29 adapted to. fit into or between the threads of the cylinder, the swivelled member or end piece being rotatably connected to the pintle by set screw 30 extending laterally through one side of the same to engage a circumferential groove 31 near the outer end of said pin-- tle. I preferably employ an ordinary form of set screw, as shown in Figs. 2 and 3, and in some instances cut'ofi the head of thescrew as ,shown in Figs. 6, 7, 13, and 21,and indicated at 30a. The member 25'of the attachment is adapted to fit over the head of the micrometergauge, the outer end of the latter being received in the socket 26, and although any I well known means may be employed for connecting these parts together screw threads are preferred, as illustrated in the drawings, it being noted that the socket in the detachable member' is countersunk to receive the shortrod 21 of the micrometer gauge, and,

that the outer surface of the body portion of said member is knurled for gripping the same inattaching and detaching it. In Figs. 2 and 3 of thedrawings I have shown two centrally spaced apart teeth 29 forming the portions which engage between the internal threads of the cylinder, but it will be underattachment hereinbefore described, this attachment for the rod comprising'an end piece of member 34 having the tooth 35 and bored fromits inner endto receive the outer end of the rod, the inner split end 34a of said end piece being slightly tapered and threaded to receive a nut 36 for clamping the attachment on the rod.

Asa modification of the form of attachments described I provide for sliding the end piece or attachmentout of engagement with the threads of the cylinder, said siidable attachment consisting of a member 37 clamped on the removable rod 38 of the micrometer gauge by nut 37a and bored at its outer end to receive a supplemental rod 39 slidablein said bore and in a sleeve 40 fitting over the reduced outer end of the member 37 to which it is secured preferably by threads and having an inwardly projecting annular flange 42 at itsouter end between which flange and outer end of the aforesaidmember a collar 43 on the rod works to limit the sliding movement of said rod, and for projecting the rod to its normal outward position a helical spring 41 is interposed between the collar on the rod and the outer end of the member over which the sleeve is attached. The rod is held at its outermost position by a nut 45 threaded on the projecting portion 44 of the rod, as shown, and the outer end of the rod is adapted to receive the attachment hereinbefore described with reference to Figs. 1 and 2.

In theoperation of the complete microme-' tel gauge shown in Fig. 2 the teeth at the ends of the attachments at both ends of'the gauge are engaged with the internal threads of the cylinder at opposite sides of the bore and the gauge is adjusted in the usual manner to obtain the measurement after the manner of the ordinary type of internal micrometer gauge, in this instance however the swivelled end piece 28 permitting the teeth at both ends of the device to properly engage the thread, and by providing the slidable rod 39 carrying the. attachment at the opposite end from the head the teeth may be placed in and out of engagement with the thread on the inner side of the cylinder without disturbing the measurement, in this operation the nut 45 being turned away from the end of the sleeve 40 a sufiicient distance to clear the thread in the cylinder. Thus it will be seen that in measuring the diameter of an internally threaded cylinder the teeth on the attachments will provide for an accurate measurement, by conta t with the walls of the threads, while the a ditional attachment forming a part of the lon er rod of the micrometer gauge and inclu ing the spring actuated auxiliary. rod will permit the length of the gauge to be shortened for fitting it in the' cylinder as well as removing it therefrom. With. respect to either attachment the teeth for engaging the internal thread of the cylinder maybe formed integrally with the, end' tion of the last mentioned detachable element being shown in Figs. 11 and 12.

In the form of my invention shown on Sheet 2 of the drawings the attachment on the head of the micrometer gauge takes the place of the usual removable short rod having the threaded shank 52 (see Fig. 22) by which it is threaded into the head and collar 53 forming a stop; my attachment in this instance comprising an end piece 54 having centrally spaced apart teeth 55 with a threaded shank 56 and stop collar 57, said shank and collar corresponding to the like parts of the removable short rod so that the attachment may be substituted therefor, and instead of a tooth on the attachment 58 at the other end of the gauge it'may be provided with an angular point 59, this attachment being also secured on' the removable rod of the gauge by means of a nut or threaded sleeve 60, and of course these attachments may be used also in connection with the slidable red attachment shown in Figs. 6, 7, and 10, and hereinbefore described, being-used in like manner to the operation described with reference to the form of my invention shown'on Sheet 1.

On this Sheet 2 of the drawings 1. have shown different forms of centrally spaced teeth which may be used on the end pieces of the attachments, Fig. 13, showing a pair of centrally spaced teeth 61--61 on the end piece 62; Fig. 14 showing a wire 63 as the engaging portion of the detachable element 64 of the end piece 65; and Fig. also showing the wire 63 on the detachable element 64 of the end piece 65 used on the rod 66 at the outer end of the gauge; while Figs. 17 and 18 show different forms of 60 angular .ends with V shape thread 67 and U..S. standard thread 68, and Fig. 19 illustrates teeth for U.- S. standard thread, while Fig. illustrates teeth for British Withwort thread, the'teeth 69 in Fig. 19 being and blunt and teeth 70 in Fig. 20, 55 and half round. Fig. 21 shows the enga'gin'gportion of the two teeth in the form of arcuate wires 71, as in Fig. 14, attached to the detachable element 72 either by sweating them on, as shown at 7 3 in Fig. 25 'or by turning the ends 63a abruptly into recesses as shown in Fig. 14, it being noted that the wires are bent into arc-shape to conform to the teeth to which they are secured and are round in cross-section the diameter of which corresponds with the pitch of the thread, and the distancebetween the centers of the'two wires also corresponds with the pitch of the threads.

From the foregoing description it will be obvious that my invention consists especially in the proposition of providing attachments for the opposite ends of an inside micrometer gauge which will not only facilitate measuring the diameter of an internally threaded cylinder but will permit the measurements to be more accurately made than by the use of the ordinary form of micrometer gauge as the measurement is taken by contact of the teeth with the walls of the threads, and it will be obvious that the attachments can be readily and cheaply applied to the conventional type of gauge such as illustrated in the drawings by simply threading the outer portion of the head or otherwise securing one of the attachments thereto, as for instance shown in Fig. 23, the other attachment being simply clamped on the outer end of the removable rod of the micrometer gauge, and consequently said attachments may be manufactured and sold in the form of attachments or in connection with the gauge.

I claim:

.1. An attachment for the outer end of the rod of amicrometer gauge for measuring the diameter of an internally threaded cylinder comprising a member mounted on the outer end of the rod, said member having a centrally cut slota-t its outer end, an inset piece lodged in the slot and secured by a pin passing through the parts transversely, said inset piece terminating in an arc-shaped tooth angular in cross-section for engaging between threads to contact with the walls thereof, and means for securing said member on the rod.

2. An attachment for the outer end of the rod of a micrometer gauge for measuring the diameter of an internally threaded cylinder comprising a member mounted on the outer end of the rod, an inset piece centrally lodged therein and having an arc-shaped groove at its outer end, and a wire secured in the groove and conforming with the shape thereof to engage between the threads of the cylinder, and means for securing said member onthe rod.

3. An attachment for the outer end of the rod of a micrometer gauge for measuring the diameter of an internally threaded cylinder comprising a member mounted on the outer end of the rod and having a centrally cut slot at its outer end, of an inset piece lodged in the slot and secured therein by a-pin passing through the parts transversely, said inset piece terminating in an arc-shaped tooth grooved at its outer end, an arc-shaped wire secured into the groove for engaging between the threads inthe cylinder, and means for securing said member on the rod.

v 4. An attachment for the outer end of the rod of a micrometer gauge for measuring the diameter of an internally threaded cylin-.

inc

der comprisin a member mounted on'the outer end of t e rod and having centrall an arc-shaped tooth grooved at its outer en an arc-shaped wire secured into the groove to enga e between the threads of the cy'linder, an

means for securing said member on the-rod.

5. An attachment for the rodof a; mi;-

crometer gauge comprising a member having means for securing the same on the outer end of the rod, a supplemental rod slidable in said member and havin means engaging the thread between the wal s thereof, and means for securing the last mentioned rod in" fixed position. v

6' An attachment for the rod of a micrometer gauge comprising a member and means for securing the same on the outer end of the rod, a supplemental rod slidable in said member. ,and having means engaging the thread between the walls thereof, means for limiting the movement of the last mentioned rod in one direction, and a springv for actuating the rod.

7. An attachment for the rod of a micrometer gauge comprising a member and means for securm end of the rod, sai member being bored mthe same-on the outer wardly from its outer end, a supplemental rod slidable insaid bore, means for. limiting the movement of the last mentioned rod in on3 direction, and a spring for actuating said ro a 8. An' attachment for the rod of a micrometer gauge comprising a. member and means-for securing the same on the outer end of the rod,'said member being bored inwardly fromits outer end, a sleeve mounted on the member to project beyond the same.

and having an internal flange at its outer end, and a supplemental rodslidable in the sleeve and bore of the'attaching member and having a collar slidable in the sleeve between said attaching member and aforesaid collar.

' 9. An attachment for the rod of a micrometer gauge comprising a member and means for securing the same on the ,outer end of the rod, said member being bored inwardly from its outer end, a sleeve mounted on the member to project beyond the same and having an internal flange at its outer end, a supplemental rod slidable inthesleeve and bore oi the attaching member and having a collar slidable in the sleeve between said attaching member and aforesaid collar, and a spring inter osed between: the collar and outer end oi t e attachin member for 1 actuatingthe supplemental ro FRANK J. IBOHN. 

